From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD144C4363D for ; Tue, 22 Sep 2020 14:30:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6842521548 for ; Tue, 22 Sep 2020 14:30:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="EvypGKA5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726631AbgIVOai (ORCPT ); Tue, 22 Sep 2020 10:30:38 -0400 Received: from smtp-fw-9102.amazon.com ([207.171.184.29]:18821 "EHLO smtp-fw-9102.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726494AbgIVOai (ORCPT ); Tue, 22 Sep 2020 10:30:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1600785038; x=1632321038; h=from:to:cc:subject:date:message-id:mime-version: in-reply-to:content-transfer-encoding; bh=4aZ5guAB6zDWL7GVzE7FWIQhgaqJUvm3Noy9tgb7BRw=; b=EvypGKA5vFnNdUFVkjtovS2HV2hmWUYH5SqRDr4J/h70lEN51j0ZbI/U pPjSRxwXpZaMq8V61uxtVdAiUmapwJ1qWqiMY6FkMik5M9sirdtIuy0fW 5D4fpd3PMKt6IRVXhQjTOCmqNEaoiuIplP87erg8BCvPpMFAfsAgZHG/0 g=; X-IronPort-AV: E=Sophos;i="5.77,291,1596499200"; d="scan'208";a="78276251" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-1a-7d76a15f.us-east-1.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-9102.sea19.amazon.com with ESMTP; 22 Sep 2020 14:30:35 +0000 Received: from EX13D31EUA004.ant.amazon.com (iad12-ws-svc-p26-lb9-vlan3.iad.amazon.com [10.40.163.38]) by email-inbound-relay-1a-7d76a15f.us-east-1.amazon.com (Postfix) with ESMTPS id 400A9A24DA; Tue, 22 Sep 2020 14:30:33 +0000 (UTC) Received: from u3f2cd687b01c55.ant.amazon.com (10.43.161.71) by EX13D31EUA004.ant.amazon.com (10.43.165.161) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 22 Sep 2020 14:30:27 +0000 From: SeongJae Park To: =?UTF-8?q?J=C3=BCrgen=20Gro=C3=9F?= CC: SeongJae Park , , , SeongJae Park , , , , , , , , Subject: Re: [PATCH v3 1/3] xen-blkback: add a parameter for disabling of persistent grants Date: Tue, 22 Sep 2020 16:30:11 +0200 Message-ID: <20200922143011.29568-1-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 In-Reply-To: <5d0f75f1-636e-e485-c616-bca47bd6932f@suse.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.43.161.71] X-ClientProxiedBy: EX13D44UWC003.ant.amazon.com (10.43.162.138) To EX13D31EUA004.ant.amazon.com (10.43.165.161) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, 22 Sep 2020 16:25:57 +0200 "Jürgen Groß" wrote: > On 22.09.20 16:15, SeongJae Park wrote: > > From: SeongJae Park > > > > Persistent grants feature provides high scalability. On some small > > systems, however, it could incur data copy overheads[1] and thus it is > > required to be disabled. But, there is no option to disable it. For > > the reason, this commit adds a module parameter for disabling of the > > feature. > > > > [1] https://wiki.xen.org/wiki/Xen_4.3_Block_Protocol_Scalability > > > > Signed-off-by: Anthony Liguori > > Signed-off-by: SeongJae Park > > --- > > .../ABI/testing/sysfs-driver-xen-blkback | 9 ++++++++ > > drivers/block/xen-blkback/xenbus.c | 22 ++++++++++++++----- > > 2 files changed, 25 insertions(+), 6 deletions(-) > > > > diff --git a/Documentation/ABI/testing/sysfs-driver-xen-blkback b/Documentation/ABI/testing/sysfs-driver-xen-blkback > > index ecb7942ff146..ac2947b98950 100644 > > --- a/Documentation/ABI/testing/sysfs-driver-xen-blkback > > +++ b/Documentation/ABI/testing/sysfs-driver-xen-blkback > > @@ -35,3 +35,12 @@ Description: > > controls the duration in milliseconds that blkback will not > > cache any page not backed by a grant mapping. > > The default is 10ms. > > + > > +What: /sys/module/xen_blkback/parameters/feature_persistent > > +Date: September 2020 > > +KernelVersion: 5.10 > > +Contact: SeongJae Park > > +Description: > > + Whether to enable the persistent grants feature or not. Note > > + that this option only takes effect on newly created backends. > > + The default is Y (enable). > > diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c > > index b9aa5d1ac10b..f4c8827fa0ad 100644 > > --- a/drivers/block/xen-blkback/xenbus.c > > +++ b/drivers/block/xen-blkback/xenbus.c > > @@ -474,6 +474,12 @@ static void xen_vbd_free(struct xen_vbd *vbd) > > vbd->bdev = NULL; > > } > > > > +/* Enable the persistent grants feature. */ > > +static bool feature_persistent = true; > > +module_param(feature_persistent, bool, 0644); > > +MODULE_PARM_DESC(feature_persistent, > > + "Enables the persistent grants feature"); > > + > > static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, > > unsigned major, unsigned minor, int readonly, > > int cdrom) > > @@ -519,6 +525,8 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, > > if (q && blk_queue_secure_erase(q)) > > vbd->discard_secure = true; > > > > + vbd->feature_gnt_persistent = feature_persistent ? 1 : 0; > > Just assign the value instead of using the ternary operator? I will do so in the next version. > > With that changed you can add my > > Reviewed-by: Juergen Gross Thank you for your kind, quick, and detailed review! Thanks, SeongJae Park